JP2022548021A - Monoalkoxysilanes and high-density organosilica films made therefrom - Google Patents

Abstract

A method for producing dense organosilicon films with improved mechanical properties comprising the steps of providing a substrate in a reaction chamber; providing a gaseous composition containing the novel monoalkoxysilane in the reaction chamber. and applying energy to the gaseous composition comprising the novel monoalkoxysilane in the reaction chamber to induce reaction of the gaseous composition comprising the novel monoalkoxysilane to the substrate wherein the organosilicon film has a dielectric constant of from about 2.80 to about 3.30, an elastic modulus of from about 9 to about 32 GPa, and from about 10 to about A method having 30 at % carbon.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of US Provisional Patent Application No. 62/899,824, filed September 13, 2019. The disclosure of that application is incorporated herein by reference in its entirety.

Compositions and methods for the formation of high density organosilica dielectric films into films using monoalkoxysilanes as precursors are described herein. More specifically, compositions and chemical vapor deposition (CVD) methods for forming dense films with dielectric constants k≧2.7, wherein the films were made from conventional precursors Compositions and chemical vapor deposition (CVD) methods are described herein that have high elastic modulus and superior resistance to plasma-induced damage compared to films.

The electronics industry utilizes dielectric materials as insulating layers between circuits and components in integrated circuits (ICs) and related electronic devices. Wiring dimensions are being reduced to increase the speed and memory storage capabilities of microelectronic devices (eg, computer chips). As the dimensions of interconnects shrink, the isolation requirements for interlayer dielectrics (ILDs) become even more stringent. Shrinking the spacing requires a lower dielectric constant to minimize the RC time constant, where R is the resistance of the conductive line and C is the capacitance of the insulating dielectric interlayer. Capacitance (C) is inversely proportional to spacing and proportional to the dielectric constant (k) of the interlevel dielectric (ILD). Conventional silica ( _SiO2 ) CVD dielectric films made from _SiH4 or TEOS (Si _{(OCH2CH3)4 , tetraethylorthosilicate} ) and _O2 have dielectric constants k greater than 4.0. There are various approaches that have been attempted in the industry to produce silica-based CVD films with lower dielectric constants, the most successful being the doping of insulating silicon oxide films with organic groups. , provides a dielectric constant of about 2.7 to about 3.5. This organosilica glass is typically prepared from an organosilicon precursor, such as methylsilane or siloxane, and an oxidizing agent, such as O ₂ or N ₂ O, as a dense film (density of about 1.5 g/cm ³ ). deposited. Organosilica glass is referred to herein as OSG.

Patents, application publications and publications in the field of porous _ILDs by the field of CVD processes are EP 1 119 035 and US Pat. describes a process for depositing OSG films from organosilicon precursors having labile groups in the presence of which subsequent thermal annealing provides porous OSG with removal of the labile groups. US Pat. Nos. 6,054,206 and 6,238,751 (teaching the removal of essentially all organic groups from deposited OSG by an oxidative anneal to yield porous inorganic SiO ₂ ); Patent Application Publication No. 1037275 (describing the deposition of a hydrogenated silicon carbide film, which is converted to porous inorganic _SiO2 by subsequent treatment with an oxidizing plasma); and U.S. Patent No. 6,312,793. Specification, WO 00/24050 (Providing co-deposition of films from organosilicon precursors and organic compounds and multi-phase OSG/organic films in which some of the polymerized organic constituents are retained) followed by a thermal anneal to do so). In the latter reference, the final final composition of the film indicates residual porogen and a large hydrocarbon film content of approximately 80-90 at %. Furthermore, the final film retains a network structure similar to SiO ₂ with some substitution of oxygen atoms for organic groups.

US Patent Application Publication No. 2011/10113184 describes a class of materials that can be used to deposit dielectric films with dielectric constants between about k=2.4 and k=2.8 by a PECVD process. disclosed. The material includes a Si compound having two hydrocarbon groups that can bond to each other to form a ring structure with the Si atom, or a Si compound having one or more branched chain hydrocarbon groups. In a branched hydrocarbon group, α-C, which is a C atom bonded to a Si atom, constitutes a methylene group, and β-C, which is a C atom bonded to a methylene group, or β-C The C atom, γ-C, is the branching point. Specifically, _two of the alkyl groups attached to Si are CH2CH( _CH3 ) _CH3 , _CH2CH ( _CH3 ) _{CH2CH3 , CH2CH2CH ( CH3} )CH ₃ , CH2C _{( CH3} ) _2CH3 and _{CH2CH2CH ( CH3} ) _{2CH3 ,} and the silicon _- bonded _third group includes _OCH3 and _OC2H5 . There are various drawbacks to this approach. The first is the need for large alkyl groups, including branched chain alkyl groups, in the precursor structure. Such molecules are expensive to synthesize and typically have high boiling points and low volatility due to their inherently high molecular weight. High boiling points and low volatility make it difficult to efficiently transport such molecules in the gas phase, as required for PECVD processes. Furthermore, the high density of SiCH ₂ Si groups in the low-k films disclosed in this approach form after the as-deposited film is exposed to UV light irradiation (i.e., after the film is UV cured). . However, the formation of SiCH ₂ Si groups after exposure to UV radiation is described, for example, in Grill, A., "PECVD low and Ultralow Dielectric Constant Materials: From Invention and Research to Products," J. Am. Vac. Sci. Technol. B, 2016, 34, 020801-1-020801-4, is well documented in the literature and thus cannot be the result of the deposition process alone. Finally, reported values for the dielectric constant in this approach are low, less than 2.8. Thus, this approach is less about depositing dense low-k films without post-deposition treatment (i.e., UV curing), and more to the tethered porogen approach for producing porous low-k films. It is closer.

Plasma or process induced damage (PID) in low-k films is caused by removal of carbon from the film during plasma exposure, particularly during etching and photoresist stripping processes. This changes the plasma damaged area from hydrophobic to hydrophilic. Exposure of the hydrophilic _SiO2 -like damaged layer to a dilute HF-based wet chemical post-plasma treatment (with or without additives such as surfactants) increases the effective dielectric constant of low-k films. , and rapid decomposition of the plasma-damaged layer. This causes feature erosion in patterned low-k wafers. Process-induced damage and induced profile erosion in low-k films is a critical issue that device manufacturers must address when incorporating low-k materials in ULSI interconnects.

Films with improved mechanical properties (higher modulus, higher hardness) reduce wire edge roughness in patterned features, reduce pattern collapse, lead to greater internal mechanical stress in interconnects, Reduce defects due to migration. Thus, for a given dielectric constant, preferably for dense low-k films with excellent resistance to PID and as high mechanical properties as possible without requiring post-deposition processing, e.g. UV curing. There is a demand for UV curing not only reduces throughput, increases cost, and increases complexity, but also reduces carbon content and introduces porosity into the film. Decreased carbon content and increased porosity cause greater plasma-induced damage. The precursors in the present invention have a dielectric constant of about 2.8-3.3, have mechanical strengths exceeding those of prior art precursors, and are free from plasma-induced damage without the need for post-deposition treatment. It is designed to deposit dense low-k films with good resistance to

The methods and compositions described herein meet one or more of the needs set forth above. Monoalkoxysilane precursors can be used to deposit dense low-k films with k values of about 2.8 to about 3.3 without the need for post-deposition processing, such The films exhibit unexpectedly high modulus/hardness and unexpectedly high resistance to plasma-induced damage.

In one aspect, the present disclosure provides a method for producing dense organosilica films with improved mechanical properties, comprising:
providing a substrate in a reaction chamber;
Formula (1) or (2):
^{( 1} ) ^R1R2MeSiOR3
(wherein R ¹ and R ² are independently selected from linear or branched C ₁ -C ₅ alkyl, preferably methyl, ethyl, propyl, iso-propyl, butyl, sec-butyl or tert-butyl) , R ³ is linear or branched C ₁ -C ₅ alkyl, preferably methyl, ethyl, propyl, iso-propyl, butyl, sec-butyl, iso-butyl or tert-butyl, more preferably iso-propyl , sec-butyl, iso-butyl and tert-butyl)
( ₂ ) ^R4 (Me) ^2SiOR5
(wherein R ⁴ is selected from linear or branched C ₁ -C ₅ alkyl, preferably methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl or tert-butyl, R ⁵ is linear or branched C ₁ -C ₅ alkyl, preferably methyl, ethyl, propyl (ie n-Pr or Pr-n), iso-propyl (ie i-Pr, Pr-i, iso- Pr, Pr-iso or Pr ⁱ ), butyl (ie n-Bu, Bu- ⁿ or Bun), sec-butyl (ie sec-Bu, Bu-sec, s-Bu, Bu-s or Bu ^s ), iso-butyl (ie iso-Bu, Bu-iso, i-Bu, Bu-i or Bu ⁱ ) or tert-butyl (tert-Bu, Bu-tert, t-Bu, Bu-t or Bu ^t ), and more preferably selected from iso-propyl, sec-butyl, iso-butyl and tert-butyl)
introducing into the reaction chamber a gaseous composition comprising a monoalkoxysilane having the structure given in Additionally, for optimum performance, the R groups form secondary or tertiary radicals upon homolytic bond dissociation (eg, SiO--R→SiO.+R., where R is a secondary or tertiary and applying energy to the gaseous composition comprising the monoalkoxysilane in the reaction chamber, inducing a reaction of a gaseous composition comprising a monoalkoxysilane to deposit an organosilicon film on a substrate, the organosilica film having a dielectric constant of about 2.8 to about 3.3 and a dielectric constant of about 9 A method is provided having a modulus of elasticity of to about 32 GPa.

In another aspect, the present disclosure provides a method for producing dense organosilica films with improved mechanical properties, comprising:
providing a substrate in a reaction chamber;
introducing a gaseous composition comprising a monoalkoxysilane into a reaction chamber; and applying energy to the gaseous composition comprising a monoalkoxysilane in the reaction chamber to form a gaseous composition comprising a monoalkoxysilane. inducing a reaction of matter to deposit an organosilica film on a substrate, the organosilica film having a dielectric constant of about 2.8 to about 3.3, an elastic modulus of about 9 to about 32 GPa, and an XPS from about 10 at% to about 30 at% carbon as measured by

4 is a graph showing the relationship between mechanical strength and percentage of Si—Me groups in a thin film. 1 is a chart showing GC-MS data for iso-propyldimethyl-iso-propoxysilane synthesized according to the method described in Example 1. FIG. formed from three precursors, di(ethyl)methyl-isopropoxysilane (DEMIPS), diethoxy-methylsilane (DEMS®) and 1-methyl-1-isopropoxy-1-silacyclopentane (MPSCP) FIG. 4 is a graph showing infrared spectra of dense low-k films; FIG. low-k for dense low-k films deposited using diethoxy-methylsilane (DEMS®) and 1-methyl-1-isopropoxy-1-silacyclopentane (MPSCP) as low-k precursors 4 is a plot of dielectric constant versus XPS carbon content for an exemplary dense low-k film deposited using di(ethyl)methyl-isopropoxysilane (DEMIPS) as a precursor.

A chemical vapor deposition method for producing dense organosilica films with improved mechanical properties, comprising:
providing a substrate in a reaction chamber;
introducing into the reaction chamber a gaseous composition comprising a _{monoalkoxysilane} , a gaseous oxidizing agent such as _O2 or N2O, and an inert gas such as He; applying energy to the gaseous composition to induce a reaction of the gaseous composition comprising the monoalkoxysilane to deposit an organosilica film on the substrate, wherein the organosilica film comprises about 2.2. a dielectric constant of about 8 to about 3.3, an elastic modulus of about 9 to about 32 GPa, and a dielectric of about 10 at% to about 30 at% carbon, preferably about 2.9 to about 3.2 as measured by XPS; A method is described herein having a modulus, a modulus of about 10 to about 29 GPa, and a carbon of about 10 at% to about 30 at% as measured by XPS.

Further, a method for producing dense organosilica films with improved mechanical properties, comprising:
providing a substrate in a reaction chamber;
introducing into the reaction chamber a gaseous composition comprising a _{monoalkoxysilane} , a gaseous oxidizing agent such as _O2 or N2O, and an inert gas such as He;
applying energy to a gaseous composition comprising a monoalkoxysilane to deposit an organosilica film on a substrate, the organosilica film having a dielectric constant of about 2.70 to about 3.3 and a dielectric constant of about 9 A method is also described herein having a modulus of elasticity of to about 32 GPa.

Monoalkoxysilanes have a higher density compared to prior art structure-forming precursors such as diethoxymethylsilane (DEMS®) and 1-isopropoxy-1-methyl-1-silacyclopentane (MESCP). organosilica films provide unique properties that allow them to achieve relatively low dielectric constants and exhibit surprisingly good mechanical properties. Without being bound by theory, the monoalkoxysilanes of the present invention have R ¹ and R ² selected from the group consisting of ethyl, propyl, iso-propyl, butyl, sec-butyl, or tert-butyl, and R ³ is methyl as disclosed in the prior art, such as Me ₃ SiOMe or Me ₃ SiOEt (Bayer, C. et al. "Overall Kinetics of SiOx Remote-PECVD using Different Organosilicon Monomers", 116-119, Surf. Coat. Technol. 874, (1999)), which provides radicals that are more stable when selected from the group consisting of methyl, ethyl, propyl, iso-propyl, butyl, sec-butyl, iso-butyl or tert-butyl, It is believed that stable radicals, such as _CH3CH2 ., ( _CH3 ) _2CH ., and _{( CH3} ) _3C ., can be provided during plasma-enhanced chemical vapor deposition. A higher density of stable radicals in the plasma such as CH ₃ CH ₂ ., (CH ₃ ) ₂ CH. and ₍ CH ₃ ) ₃ C. increases the probability of extraction of hydrogen atoms from the SiCH 2 (formation of SiCH ₂ ) and facilitates the formation of disilylmethylene groups (ie, Si--CH ₂ --Si moieties) in the as-deposited film. Presumably, in molecules of the R ¹ Me ₂ SiOR ³ type, the higher density of terminal silicon methyl groups (two per silicon atom) in the precursor leads to a higher density of disilylmethylenes in the as-deposited film. It further aids in the formation of the group (Si--CH ₂ --Si).

In organic chemistry, more energy must be supplied to produce a primary carbon radical (e.g. the ethyl radical CH3CH2.) than a _secondary carbon radical (e.g. the isopropyl radical _{( CH3} ) _2CH .). It is well known. This is due to the higher stability of the isopropyl radical relative to the ethyl radical. The same principle applies to homolytic bond dissociation of oxygen-carbon bonds in silicon alkoxy groups; less energy is required to dissociate the oxygen-carbon bond in isopropoxysilane than in ethoxysilane. Similarly, less energy is required to dissociate the silicon-carbon bond in isopropylsilane than in ethylsilane. It is speculated that bonds that require less energy to break are more likely to dissociate in the plasma. Therefore, monoalkoxysilanes with Si--OPr ⁱ , Si-- ^{OBus or Si--OBu t groups} have a higher density of SiO-type radicals in plasma than those with Si--OEt groups. can bring Similarly, monoalkoxysilanes with Si--Et, Si--P ⁱ , Si--Bu ^s or Si--Bu ^t groups have higher densities in plasma compared to those with only Si--Me groups. Si-type radicals can be provided. Presumably, this is due to the differentiated properties of those deposited using monoalkoxysilanes with Si—OPr ⁱ , Si—OBu ^s or Si—OBu ^t groups versus monoalkoxysilanes with Si—OEt. contribute.

Some of the advantages over the prior art achieved with monoalkoxysilanes as silicon precursors include, but are not limited to:
Ease of synthesis and low cost High modulus/high hardness Wide range of XPS carbons Contains high disilylmethylene densities.

Table 1 lists selected monoalkoxysilanes having formulas 1 and 2. Although many compounds are disclosed, the most preferred molecules are alkyl groups ( ^R1 , ^R2 , R3 ^{, R4} ) selected such that the boiling point of the molecule is less than 200°C (preferably less than 150°C). and R ⁵ ). Additionally, for optimum performance, the R ¹ , R ² , R ³ , R ⁴ and R ⁵ groups, some or all of which upon homolytic bond dissociation form secondary or tertiary radicals ( For example, Si--R ² →Si.+R ^2. or SiO--R ³ →SiO.+R ^3. , where R ² and R ³ are secondary or tertiary radicals, such as isopropyl radical, sec-butyl radical. , a tert-butyl radical or a cyclohexyl radical). The most preferred example is di-iso-propylmethyl(iso-propoxy)silane, which has a predicted boiling point of 168°C at 760 Torr.

Table 1 List of exemplary monoalkoxysilanes having formulas 1 and 2

Prior art silicon-containing structure-forming precursors, such as DEMS®, polymerize after being excited in a reaction chamber to form structures with --O-- bonds in the polymer backbone (eg, --Si--O--Si - or Si-O-C-) and having the formula (1) or formula (2), monoalkoxysilane compounds such as DEMIPS molecules polymerize to form a high proportion of -O- crosslinks in the main chain. -CH ₂ -methylene or -CH ₂ CH ₂ -ethylene bridges to form structures that are substituted. %Si—Me (directly related to %C) and mechanical strength in films deposited using DEMS® as the structure-forming precursor, where carbon is predominantly present in the form of Si—Me groups. There is a relationship between, see, for example, the model work shown in FIG. Here, the replacement of the bridging Si--O--Si groups by two terminal Si--Me groups reduces the mechanical properties due to the disruption of the network structure. In the case of monoalkoxysilane compounds of formula (1) or formula (2), it is believed that the precursor structure is disrupted during film deposition to form SiCH ₂ Si or SiCH ₂ CH ₂ Si bridging groups. In this way carbon in the form of bridging groups can be incorporated so that from a mechanical strength point of view an increase in the carbon content in the film does not disrupt the network structure. While not wishing to be bound by theory, this property makes the film susceptible to carbon depletion in dense films by processes such as film etching, photoresist plasma ashing, and copper surface _NH3 plasma treatment. Carbon is added to the film to make it more resilient. Carbon depletion in dense low-k films increases the effective dielectric constant of the film, problems with film etching, and feature bending during wet clean steps and/or integration when depositing copper diffusion barriers. can cause problems. Prior art structuring agents, such as MESCP, can deposit low-k films with a very high density of crosslinked SiCH ₂ Si and/or SiCH ₂ CH ₂ Si groups, but these films ultimately It also has a very high Si—Me density and total carbon content that limits the highest elastic modulus that can be achieved with this class of prior art low-k precursors.

Preferably, compositions comprising monoalkoxysilanes having formulas 1 and 2 according to the invention and monoalkoxysilane compounds having formulas 1 and 2 according to the invention are substantially free of halide ions. As used herein, the term "substantially free" refers to halide ions (or halides), such as chlorides (ie, chloride-containing species such as HCl or silicon compounds having at least one Si—Cl bond ), for fluorides, bromides and iodides, less than 5 ppm (by weight) as measured by ion chromatography (IC), preferably less than 3 ppm as measured by IC, more preferably less than 1 ppm as measured by IC means less than, most preferably 0 ppm as measured by IC. Chlorides are known to act as decomposition catalysts for silicon precursor compounds. Significant levels of chloride in the final product can decompose the silicon precursor compound. Slow decomposition of the silicon precursor compound can directly affect the film deposition process and make it difficult for semiconductor manufacturers to meet film specifications. In addition, shelf life or stability is negatively impacted by the faster decomposition rate of silicon precursor compounds, thereby making it difficult to guarantee a shelf life of 1-2 years. Accordingly, accelerated decomposition of silicon precursor compounds raises safety and performance concerns regarding the formation of these flammable and/or pyrophoric gaseous by-products. Preferably, the monoalkoxysilanes having formulas 1 and 2 contain metal ions such as Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ca ²⁺ , Al ³⁺ , Fe ²⁺ , Fe ²⁺ , Fe ³⁺ , Ni ²⁺ and Cr ³⁺ are not substantially contained. As used herein, the term "substantially free" when relating to Li, Na, K, Mg, Ca, Al, Fe, Ni, Cr, when measured by ICP-MS (by weight ) less than 5 ppm, preferably less than 3 ppm, more preferably less than 1 ppm, most preferably less than 0.1 ppm. In some embodiments, the silicon precursor compound having formula A contains metal ions such as Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ca ²⁺ , Al ³⁺ , Fe ²⁺ , Fe ²⁺ , Does not contain Fe ³⁺ , Ni ²⁺ , Cr ³⁺ . As used herein, the term "free of" metallic impurities is less than 1 ppm when referring to Li, Na, K, Mg, Ca, Al, Fe, Ni, Cr, preferably measured by ICP-MS means less than 0.1 ppm (by weight), most preferably less than 0.05 ppm (by weight) as determined by ICP-MS or other analytical method for determining metals. Additionally, preferably the monoalkoxysilanes having formulas 1 and 2 have a purity of 98 wt% or greater, preferably 99 wt% as measured by GC when used as precursors for depositing silicon-containing films. or higher purity.

The low-k dielectric film is an organic silica glass (“OSG”) film or material. Organosilicates are used, for example, as low-k materials in the electronics industry. Material properties depend on the chemical composition and structure of the film. The type of organosilicon precursor has such a strong effect on the structure and composition of the film that imparting the amount of porosity required to reach the desired dielectric constant produces a mechanically unsound film. It is beneficial to use precursors that provide the required film properties to ensure that no The methods and compositions described herein produce and improve low-k dielectric films with a desired balance of electrical and mechanical properties, as well as other beneficial film properties such as high carbon content. provide a means of providing a controlled integrated plasma resistance.

In certain embodiments of the methods and compositions described herein, the layer of silicon-containing dielectric material is deposited on at least a portion of the substrate via a chemical vapor deposition (CVD) process using a reaction chamber. deposited. Accordingly, the method includes providing a substrate in the reaction chamber. Suitable substrates include, but are not limited to, semiconductor materials such as gallium arsenide (“GaAs”), silicon, and silicon-containing compositions such as crystalline silicon, polysilicon, amorphous silicon, epitaxial Silicon, silicon dioxide (“SiO ₂ ”), silicon glass, silicon nitride, fused silica, glass, quartz, borosilicate glass and combinations thereof. Other suitable materials include chromium, molybdenum, and other metals commonly used in semiconductor, integrated circuit, flat panel display and flexible display applications. The substrate may be coated with further layers such as silicon, _SiO2 , organosilicate glass (OSG), fluorinated silicate glass (FSG), boron carbonitride, silicon carbide, hydrogenated silicon carbide, silicon nitride, hydrogenated nitride. Metal oxides such as silicon, silicon carbonitride, hydrogenated silicon carbonitride, boron nitride, organic-inorganic composites, photoresists, organic polymers, porous organic and inorganic materials and composites, aluminum oxide and germanium oxide You can have things. Further layers may include germanosilicates, aluminosilicates, copper and aluminum, and diffusion barrier materials such as, but not limited to, TiN, Ti(C)N, TaN, Ta(C)N, Ta , W or WN.

Typically, the reaction chamber is, for example, a thermal CVD or plasma-enhanced CVD reactor, or a batch furnace type reactor in various methods. In one embodiment, a liquid transport system can be utilized. In liquid delivery formulations, the precursors described herein can be delivered in undiluted liquid form or, alternatively, in solvent formulations containing the precursors described herein. or can be used in the composition. Thus, in certain embodiments, the precursor formulation comprises one or more solvents of suitable characteristics that may be desired and advantageous for forming a film on a substrate in a given end-use application. may contain constituents.

The methods disclosed herein include introducing a gaseous composition comprising a monoalkoxysilane into a reaction chamber. In some embodiments, the composition may include additional reactants such as oxygen _- containing species such as _{O2 ,} O3 and N2O, gaseous or liquid organic substances, _CO2 or CO. _{In one} particular embodiment, the reaction mixture introduced into the reaction chamber is from the group consisting of _O2 , N2O, NO, _NO2 , _CO2 , water, _H2O2 , ozone and combinations thereof. At least one selected oxidizing agent is included. In an alternative embodiment, the reaction mixture does not contain an oxidizing agent.

The compositions for depositing dielectric films described herein contain from about 40 to about 100 wt% monoalkoxysilane.

In embodiments, gaseous compositions containing monoalkoxysilanes can be used with curing additives to further increase the modulus of as-deposited films.

In embodiments, the gaseous composition comprising the monoalkoxysilane is substantially free or free of halides, such as chlorides.

In addition to the monoalkoxysilane, additional materials can be introduced into the reaction chamber before, during and/or after the deposition reaction. Such materials can be used, for example, as an inert gas (e.g., as a carrier gas for lower volatility precursors) and/or promote curing of the as-deposited material to make it more stable. He, Ar, N ₂ , Kr, Xe, etc.), which can provide an excellent final film.

Any of the reagents used, including the monoalkoxysilane, can be transported into the reactor either separately from another source or as a mixture. Reagents can be transported to the reactor system by any number of means, preferably using a pressurizable stainless steel vessel, fitted with suitable valves, that allows transport of the liquid to the process reactor. can. Preferably, the precursor is transported into the process vacuum chamber as a gas, ie the liquid must be vaporized before being transported into the process chamber.

The methods disclosed herein apply energy to a gaseous composition comprising a monoalkoxysilane in a reaction chamber to induce a reaction of the gaseous composition comprising a monoalkoxysilane to form a substrate. wherein the organosilica film is from about 2.8 to about 3.3 in some embodiments, from 2.90 to 3.2 in other embodiments, and more preferred implementations. Embodiments have a dielectric constant of 3.0 to 3.2, a modulus of elasticity of about 9 to about 32 GPa, preferably 10 to 29 GPa, and carbon of about 10 to about 30 at % as measured by XPS. Energy is applied to the gaseous reagent to induce the monoalkoxysilane, and other reactants, if present, to react to form a film on the substrate. Such energy can be provided by, for example, plasma, pulsed plasma, helicon plasma, high density plasma, inductively coupled plasma, remote plasma, hot filament and thermal (ie, non-filament) methods. A secondary rf frequency source can be used to modify the plasma properties at the substrate surface. Preferably, the film is formed by plasma enhanced chemical vapor deposition (“PECVD”).

Preferably, the flow rate for each of the gaseous reagents is between 10 and 5000 sccm, more preferably between 30 and 3000 sccm, per single 300 mm wafer. The actual flow rate required may depend on wafer size and chamber configuration and is in no way limited to 300 mm wafers or single wafer chambers.

In certain embodiments, the film is deposited at a deposition rate of about 5 to about 700 nanometers (nm) per minute. In another embodiment, the film is deposited at a deposition rate of about 30-200 nanometers (nm) per minute.

Typically, the pressure in the reaction chamber during deposition is from about 0.01 to about 600 torr, or from about 1 to 15 torr.

Preferably, the film is deposited to a thickness of 0.001 to 500 microns, although the thickness can vary as desired. A blanket film deposited on an unpatterned surface has a 3% It has excellent uniformity with thickness variations of less than /1 standard deviation.

In addition to the OSG products of the invention, the invention includes processes for making the products, methods of using the products, and compounds and compositions useful for preparing the products. For example, a process for manufacturing integrated circuits on semiconductor devices is disclosed in US Pat. No. 6,583,049, incorporated herein by reference.

Dense organosilica films produced by the disclosed method exhibit good resistance to plasma-induced damage, especially during etching and photoresist stripping processes.

For a given dielectric constant, dense organosilica films produced by the disclosed method have the same dielectric constant, but are compared to dense organosilica films made from precursors that are not monoalkoxysilanes. Exhibits excellent mechanical properties. Typically, the resulting (as-deposited) organosilica films have a thickness of from about 2.8 to about 3.3 in some embodiments and from about 2.9 to about 3.0 in other embodiments. 2, in still other embodiments having a dielectric constant of from about 3.0 to about 3.2, an elastic modulus of from about 9 to about 32 GPa, and from about 10 to about 30 at% carbon as measured by XPS. In other embodiments, the resulting organosilica films have a dielectric constant of from about 2.9 to about 3.2 in some embodiments, from about 3.0 to about 3.20 in other embodiments, and It has a modulus of elasticity from about 9 to about 32 GPa. In other embodiments, the resulting organosilica films have an elastic modulus of from about 10 to about 29 in some embodiments, from about 11 to about 29 in other embodiments, and a modulus of about 10 as measured by XPS. - about 30 at% carbon.

The resulting dense organosilica film may undergo post-treatment processes after being deposited. Thus, as used herein, the term "post-treatment" refers to treating the film with energy (e.g., heat, plasma, photons, electrons, microwaves, etc.) or chemicals to further enhance the properties of the material. means that

The conditions under which the post-treatment takes place can vary greatly. For example, post-treatment may be performed under high pressure or under a vacuum atmosphere.

UV annealing is the preferred method performed under the following conditions.

The environment can be inert (e.g. nitrogen, _CO2 , noble gases (He, Ar, Ne, Kr, Xe), etc.), oxidizing (e.g. oxygen, air, lean oxygen environment, rich oxygen environment, ozone, nitrous oxide). etc.) or reducible (lean or enriched hydrogen, hydrocarbons (saturated, unsaturated, straight or branched chain, aromatic), etc.). Preferably, the pressure is from about 1 Torr to about 1000 Torr. However, for thermal annealing as well as any other post-treatment means, a vacuum atmosphere is preferred. Preferably, the temperature is 200-500° C. and the temperature ramp rate is 0.1-100° C./min. Preferably, the total UV annealing time is 0.01 minutes to 12 hours.

The invention is illustrated in more detail with reference to the following examples, but it should not be understood that they are considered to be limited to the following examples. Using the precursors described in this invention, similar process advantages over existing porous low-k films (i.e., higher resistance to plasma-induced damage for a given value of dielectric constant, and higher It is also recognized that porous low-k films with high elastic modulus) can also be deposited.

Example 1: Synthesis of di(ethyl)methyl-iso-propoxysilane In a 500 mL flask Ru ₃ (CO) ₁₂ was dissolved in 20 g THF. Then 200 g (3.33 mol) of IPA (isopropyl alcohol) was added. The solution was heated to 75°C. While stirring, 200 g (1.96 mol) of di(ethyl)methylsilane was added dropwise through an addition funnel. The reaction was exothermic and hydrogen bubbles were observed. After the addition was complete, the reaction mixture was stirred at room temperature for 30 minutes. Excess IPA and THF were removed by distillation at atmospheric pressure. 250 g of di(ethyl)methyl-iso-propoxysilane (99.3% purity) with a boiling point of 63° C. at 55 mm Hg was produced by fractional vacuum distillation. Yield was 80%. GC-MS: 160 (M+), 145, 131, 101, 88, 73, 61, 45.

Example 2: Synthesis of di(methyl)-iso-propyl-iso-propoxysilane 992 mL (1.98 mol) of 2M isopropylmagnesium chloride in THF was added at room temperature to 303.0 g (1.98 mol) in 1 L of hexane. of di(methyl)-iso-propylchlorosilane. The reaction mixture was slowly warmed to a temperature of 60°C. After the addition was complete, it was allowed to cool to room temperature and stirred overnight. The resulting light gray slurry was filtered. Solvent was removed by distillation. The product was distilled at atmospheric pressure. 218 g of di(methyl)iso-propyl-iso-propoxysilane with a boiling point of 134° C. were produced by fractional vacuum distillation. FIG. 2 is a chart showing GC-MS data of synthesized di(methyl)iso-propyl-iso-propoxysilane. Yield was 69%. GC-MS: 160 (M+), 145, 117, 101, 87, 75, 49, 45.

All deposition experiments below were performed on a 300 mm AMAT Producer® SE that deposited films on two wafers simultaneously. Thus, the precursor and gas flow rates correspond to those required to deposit films on two wafers simultaneously. The stated per-wafer RF power is correct when each wafer processing station has its own independent RF power supply. The stated deposition pressure is correct when both wafer processing stations are held at the same pressure. The Producer® SE was equipped with a Producer® Nanocure chamber used to UV cure certain films after the deposition process was completed.

Although illustrated and described above with reference to certain specific embodiments and examples, nevertheless, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the spirit of the invention. For example, all ranges recited broadly in this document are expressly intended to include within those ranges all narrower ranges within the broader range. The compounds disclosed in formulas (1) and (2) in the present invention are also useful for the deposition of porous low-k films with high elastic modulus, high XPS carbon content, and high resistance to plasma-induced damage. It is recognized that it can be used as a structuring agent for

Thickness and refractive index were measured on a Woollam model M2000 spectroscopic ellipsometer. Dielectric constants were determined using the Hg probe technique on medium resistivity p-type wafers (8-12 Ω·cm). FTIR spectra were measured using a Thermo Fisher Scientific Model iS50 spectrometer equipped with a nitrogen purged Pike Technologies Map300 to process 12 inch wafers. FTIR spectra were used to calculate the relative density of bridging disilylmethylene groups in the film. The total density of terminal silicon methyl groups (i.e., the density of Si—Me or Si(CH ₃ ) _x , where x is 1, 2 or 3) in the film, as determined by infrared spectroscopy, is Define the area of the Si(CH ₃ ) _x infrared band centered around 1270 cm ⁻¹ as 100 times divided by the area of the SiO _x band from approximately 1250 cm ⁻¹ to 920 cm ⁻¹ . The relative density of bridging disilylmethylene groups in the film (i.e., the density of _SiCH2Si ), as determined by infrared spectroscopy, is approximately equal to the area of the _SiCH2Si infrared band centered around 1360 cm ^-1 . Defined as 10000 times divided by the area of the SiO _x band from 1250 cm ⁻¹ to 920 cm ⁻¹ . Mechanical properties were determined using a KLA iNano nanoindenter.

Compositional data were obtained by X-ray photoelectron spectroscopy (XPS) on either a PHI 5600 (73560, 73808) or Thermo K-Alpha (73846) and are provided in atomic weight percent. The atomic weight percent (%) values reported in the table do not include hydrogen.

For each precursor in the examples listed below, the deposition conditions were optimized to produce films with high mechanical properties at dielectric constants of 3.1 or 3.2.

Comparative Example 3: Deposition of Dense, Diethoxymethylsilane (DEMS®)-Based Films Dense, DEMS®-based films were deposited using the following process conditions for 300 mm processing. deposited. The DEMS® precursor was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 750 mg/min using a He carrier gas flow of 1500 sccm and a 380 milliinch showerhead/heating. A 13.56 MHz plasma of 300 Watts was applied at a pedestal temperature of 345° C., a chamber pressure of 10 Torr, and a pedestal spacing of 300 watts. Various properties of the film (e.g. dielectric constant (k), elastic modulus, hardness, density of various functional groups as determined by infrared spectroscopy, and atomic composition (%C, %O and %Si) by XPS). was obtained as described above and is provided in Table 2.

Comparative Example 4: Deposition of Dense, Diethoxymethylsilane (DEMS®)-Based Films Dense, DEMS®-based films were deposited using the following process conditions for 300 mm processing. deposited. The DEMS® precursor was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 750 mg/min using a He carrier gas flow of 2250 sccm and a 380 milliinch showerhead/heating. A 13.56 MHz plasma of 200 Watts was applied at a pedestal temperature of 345° C., a chamber pressure of 10 Torr, and a pedestal spacing of 200 watts. Various properties of the film (e.g. dielectric constant (k), elastic modulus, hardness, density of various functional groups as determined by infrared spectroscopy, and atomic composition (%C, %O and %Si) by XPS). was obtained as described above and is provided in Table 3.

Comparative Example 5: Deposition of a dense, 1-methyl-1-isopropoxy-1-silacyclopentane (MESCP)-based film A dense, MPSCP-based film was deposited under the following process conditions for 300 mm processing. deposited using. The MPSCP precursor was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 850 mg/min using a He carrier gas flow of 750 sccm and a showerhead/heated pedestal spacing of 380 milliinch. at a substrate temperature of 390 °C, a chamber pressure of 7.5 Torr, and a 13.56 MHz plasma of 225 Watts applied, various properties of the film (e.g. dielectric constant (k), elastic modulus, hardness, infrared spectroscopy). The densities of various functional groups as measured by , and atomic compositions by XPS (%C, %O and %Si)) were obtained as described above and are provided in Table 2.

Comparative Example 6: Deposition of a dense, 1-methyl-1-isopropoxy-1-silacyclopentane (MPSCP)-based film A dense, MPSCP-based film was deposited under the following process conditions for 300 mm processing. The MPSCP precursor, deposited using a / A 13.56 MHz plasma of 275 Watts was applied at a pedestal temperature of 390° C. and a chamber pressure of 7.5 Torr at a heated pedestal interval. Various properties of the film (e.g. dielectric constant (k), elastic modulus, hardness, density of various functional groups as measured by infrared spectroscopy, and atomic composition (%C, %O and %Si) by XPS). was obtained as described above and is provided in Table 3.

Example 7: Deposition of a dense, di(ethyl)methyl-isopropoxysilane (DEMIPS)-based film A dense, di(ethyl)methyl-isopropoxysilane-based film was deposited by the following process for 300 mm processing. Deposited using conditions. Di(ethyl)methyl-isopropoxysilane precursor was transported into the reaction chamber via direct liquid injection (DLI) at a flow rate of 850 mg/min using a He carrier gas flow of 750 sccm and O A 13.56 MHz plasma of 225 Watts was applied at a flow rate of ₂ , a showerhead/heated pedestal spacing of 380 milliinch, a pedestal temperature of 390° C., a chamber pressure of 7.5 Torr. Various properties of the film (e.g. dielectric constant (k), elastic modulus, hardness, density of various functional groups as measured by infrared spectroscopy, and atomic composition (%C, %O and %Si) by XPS). was obtained as described above and is provided in Table 2.

Example 8: Deposition of dense, di(ethyl)methyl-isopropoxysilane-based films A dense, di(ethyl)methyl-isopropoxysilane-based film was deposited using the following process conditions for a 300 mm process. and deposited. Di(ethyl)methyl-isopropoxysilane precursor was transported into the reaction chamber via direct liquid injection (DLI) at a flow rate of 850 mg/min using a He carrier gas flow of 750 sccm and O A 13.56 MHz plasma at 275 Watts was applied at a flow rate of ₂ , a showerhead/heated pedestal spacing of 380 mm, a pedestal temperature of 390° C., a chamber pressure of 7.5 Torr. Various properties of the film (e.g. dielectric constant (k), elastic modulus, hardness, density of various functional groups as measured by infrared spectroscopy, and atomic composition (%C, %O and %Si) by XPS). was obtained as described above and is provided in Table 3.

Process conditions for the deposition of dense low-k films deposited using DEMIPS, DEMS® and MPSCP as low-k precursors in a 300 mm PECVD reactor are given in Table 2 below. The processing conditions for each of these depositions were adjusted to obtain a high modulus with a dielectric constant of 3.1. The infrared spectra of the dense low-k films of Table 2 are shown in Table 3. The relative density of Si(CH ₃ ) _x and SiCH ₂ Si groups in each film was calculated from its infrared spectrum previously described.

A series of dense low-k dielectric film depositions were performed using DEMIPS, DEMS® or MPSCP as low-k precursors in a PECVD reactor at 170-425 Watts plasma power, 7.5- 10 Torr chamber pressure, 345-390° C. substrate temperature, 0-30 sccm O ₂ gas flow, 600-2250 sccm He carrier gas flow, 0.75-2.0 g/min precursor liquid flow, and 0.75-2.0 g/min precursor liquid flow. Deposited under various process conditions with an electrode spacing of 380 inches. Carbon content was measured by XPS as described herein. FIG. 4 shows the relationship between the carbon content (at %) of dense DEMIPS, DEMS® and MPSCP® films with different dielectric constants. As FIG. 4 shows, prior art or DEMS® low-k films exhibit a narrow range of carbon content of about 17-22 at % as the dielectric constant increases from about 2.75 to about 3.45. had FIG. 4 also shows that the prior art or MPSCP bottom-k films had a wider range of carbon content, from about 19 to about 42 at % for the same range of dielectric constants. DEMIPS films also have a wide range of carbon contents from about 12 to 31 at. less than the carbon content of the film. This demonstrates that using the monoalkoxysilane compounds of formula (1) or formula (2) described herein as DEMIPS yields dense low-k dielectric films with similar values of dielectric constant. Demonstrating one of the key advantages over using other prior art structuring agents for deposition, the monoalkoxysilane precursor DEMIPS has a lower total With carbon, the total carbon is higher than prior art precursors such as DEMS®, allowing for a wide adjustable range of carbon content.

Table 2 provides a comparison of dense low-k films with a dielectric constant of k=3.1 using DEMIPS, DEMS® and MPSCP as low-k precursors. The processing conditions for the given films were adjusted to obtain high modulus without post-treatment such as UV curing. Compared to prior art DEMS® and MPSCP-based films with low carbon content, DEMIPS films have a significantly higher elastic modulus (about +20%). In addition, the DEMIPS film has a higher carbon content (approximately +23%), a lower density of Si(CH ₃ ) groups (approximately −30%), and a higher It has a density of SiCH ₂ Si groups (about +40%). In addition, DEMIPS films have a lower carbon content (approximately −40%), a lower density of Si(CH ₃ ) groups (approximately −45%), and a lower SiCH ₂ Si It has a base density (approximately -40%). This demonstrates that using the monoalkoxysilane compounds of formula (1) or formula (2) described herein as DEMIPS yields dense low-k dielectric films with similar values of dielectric constant. Showing significant advantages over using other prior art structuring agents for deposition, the monoalkoxysilane precursor DEMIPS exhibits a very high elastic modulus, a wide tunable range of carbon content, It enables the deposition of low-k dielectric films with low Si(CH ₃ ) group densities and high SiCH ₂ Si group densities. For the same value of dielectric constant, DEMIPS-based films have a higher total carbon content than prior art precursor-based films such as DEMS®, which result in films with lower total carbon content. , and have a lower total carbon content than prior art precursor-based films such as MPSCP, which results in films with higher total carbon content. This suggests that the very high carbon content and high Si( _CH3 ) density of prior art MPSCP-based films ultimately lead to the highest modulus obtainable using this class of precursors. This is a very important difference because it limits On the other hand, prior art precursors such as DEMS®, which lead to films with low carbon content, have carbon in the oxide network mainly Si(CH ₃ ) instead of SiCH ₂ Si. as a radical, thus limiting the maximum elastic modulus that can be obtained with this class of precursors. In addition, low carbon content prior art precursors such as DEMS® have limited resistance to plasma induced damage (PID) due to their low carbon content. This demonstrates that using the monoalkoxysilane compounds of formula (1) or formula (2) described herein as DEMIPS yields dense low-k dielectric films with similar values of dielectric constant. Showing another important advantage over using other prior art structuring agents for deposition, the monoalkoxysilane precursor DEMIPS compares to prior art precursors such as DEMS® allows deposition of films with high modulus, high resistance to plasma-induced damage due to its moderate carbon content, low density of Si( _CH3 ) groups, and high density of _SiCH2Si groups. and In fact, the combination of high modulus, moderate carbon content, low Si( _CH3 ) density, and high _SiCH2Si density leads to the deposition of low-k films with higher carbon content than DEMIPS-based films. It is expected to provide similar resistance to PID as prior art precursors, such as MPSCP, which lead to

Table 2. Processing conditions for a selective membrane with a dielectric constant of 3.1 adjusted to obtain a high modulus

Table 3 provides a comparison of dense low-k films with a dielectric constant of k=3.2 using DEMIPS, DEMS® and MPSCP as low-k precursors. The processing conditions for the given films were adjusted to obtain high modulus without post-treatment such as UV curing. Compared to prior art DEMS® and MPSCP-based films with low carbon content, DEMIPS-based films have significantly higher elastic moduli (about +16-20%). In addition, the DEMIPS film has a higher carbon content (approximately +57%), a lower density of Si(CH ₃ ) groups (approximately −20%), and a higher It has a density of SiCH ₂ Si groups (about +35%). In addition, DEMIPS films have a lower carbon content (approximately −33%), a lower density of Si(CH ₃ ) groups (approximately −41%), and a lower SiCH ₂ Si It has a base density (approximately -36%). This demonstrates that using the monoalkoxysilane compounds of formula (1) or formula (2) described herein as DEMIPS yields dense low-k dielectric films with similar values of dielectric constant. Showing significant advantages over using other prior art structuring agents for deposition, the monoalkoxysilane precursor DEMIPS exhibits a very high elastic modulus, a wide tunable range of carbon content, It enables the deposition of low-k dielectric films with low Si(CH ₃ ) group densities and high SiCH ₂ Si group densities. For the same value of dielectric constant, DEMIPS-based films have a higher total carbon content than prior art precursor-based films such as DEMS® and prior art precursor-based films such as MPSCP. have a lower total carbon content than the films of This suggests that the very high carbon content and high Si( _CH3 ) density of prior art MPSCP-based films ultimately lead to the highest modulus obtainable using this class of precursors. This is a very important difference because it limits On the other hand, prior art precursors such as DEMS®, which lead to films with low carbon content, have carbon in the oxide network mainly Si(CH ₃ ) instead of SiCH ₂ Si. as a radical, thus limiting the maximum elastic modulus that can be obtained with this class of precursors. In addition, low carbon content prior art precursors such as DEMS® have limited resistance to plasma induced damage (PID) due to their low carbon content. This demonstrates that using the monoalkoxysilane compounds of formula (1) or formula (2) described herein as DEMIPS yields dense low-k dielectric films with similar values of dielectric constant. Showing another important advantage over using other prior art structuring agents for deposition, the monoalkoxysilane precursor DEMIPS compares to prior art precursors such as DEMS® This allows deposition of films with higher elastic modulus and higher resistance to expected induced damage. This is due to higher carbon content, lower density of Si( _CH3 ) _x groups, and higher This is due to the density of SiCH ₂ Si groups. In fact, the combination of high modulus, moderate carbon content, low Si( _CH3 ) _x density, and high _SiCH2Si density suggests that MPSCP-based films have a higher carbon content than DEMIPS-based films. It is expected to provide similar resistance to PID as prior art precursors such as MPSCP, despite resulting in k film deposition.

Table 3. Processing conditions for a selective membrane with a dielectric constant of 3.2, adjusted to obtain a high modulus

Claims (16)

A method for producing a dense organosilica film with improved mechanical properties, comprising:
introducing a substrate into a reaction chamber;
Formula (1) or (2):
^{( 1} ) ^R1R2MeSiOR3
(wherein R ¹ and R ² are independently selected from linear or branched C ₁ -C ₅ alkyl, preferably ethyl, propyl, iso-propyl, butyl, sec-butyl or tert-butyl; ³ is selected from linear or branched C ₁ -C ₅ alkyl, preferably methyl, ethyl, propyl, iso-propyl, butyl, sec-butyl, iso-butyl or tert-butyl)
( ₂ ) ^R4 (Me) ^2SiOR5
(wherein R ⁴ is selected from linear or branched C ₁ -C ₅ alkyl, preferably ethyl, propyl, iso-propyl, butyl, sec-butyl or tert-butyl, and R ⁵ is linear or branched or branched C ₁ -C ₅ alkyl, preferably selected from ethyl, propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl or tert-butyl)
A gaseous composition comprising a monoalkoxysilane having the structure given in substantially free of one or more impurities selected from the group consisting of halides, water, metals and combinations thereof. introducing a substance into the reaction chamber; and applying energy to the gaseous composition comprising monoalkoxysilane in the reaction chamber to induce reaction of the gaseous composition comprising monoalkoxysilane. and depositing an organosilica film on said substrate, said organosilica film having a dielectric constant of about 2.8 to about 3.30 and an elastic modulus of about 9 to about 32 GPa. 2. The method of claim 1, wherein said gaseous composition comprising a monoalkoxysilane does not contain a curing additive. 2. The method of claim 1, which is a chemical vapor deposition method. 2. The method of claim 1, which is a plasma enhanced chemical vapor deposition method. wherein said gaseous composition comprising a _{monoalkoxysilane} is at _least selected from the group consisting of _O2 , N2O, NO, _NO2 , _CO2 , CO, water, _H2O2 , ozone and combinations thereof; 2. The method of claim 1, further comprising one oxidizing agent. 2. The method of claim 1, wherein the gaseous composition containing monoalkoxysilanes does not contain an oxidizing agent. 2. The method of claim 1, wherein the reaction chamber in the applying step contains at least one gas selected from the group consisting of He, Ar, _N2 , Kr, Xe, _CO2 and CO. 2. The organosilica film of claim 1, wherein the organosilica film has a refractive index (RI) of about 1.3 to about 1.6 at 632 nm and a carbon content of about 10 at% to about 30 at% as measured by XPS. the method of. 2. The method of claim 1, wherein the organosilica film is deposited at a rate of about 5 nm/min to about 700 nm/min. 9. The method of claim 8, wherein the organosilica film has an IR ratio of SiCH ₂ Si/SiO _x x10 ⁴ from about 8 to about 30. A composition for vapor deposition of dielectric films, comprising formula (1) or (2):
^{( 1} ) ^R1R2MeSiOR3
(wherein R ¹ and R ² are independently selected from linear or branched C ₁ -C ₅ alkyl, preferably ethyl, propyl, iso-propyl, butyl, sec-butyl or tert-butyl; ³ is selected from linear or branched C ₁ -C ₅ alkyl, preferably methyl, ethyl, propyl, iso-propyl, butyl, sec-butyl, iso-butyl or tert-butyl)
( ₂ ) ^R4 (Me) ^2SiOR5
(wherein R ⁴ is selected from linear or branched C ₁ -C ₅ alkyl, preferably ethyl, propyl, iso-propyl, butyl, sec-butyl or tert-butyl, and R ⁵ is linear or branched or branched C ₁ -C ₅ alkyl, preferably selected from ethyl, propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl or tert-butyl)
A composition comprising a monoalkoxysilane having the structure given in is substantially free of one or more impurities selected from the group consisting of halides, water and metals. the monoalkoxysilane is di(ethyl)-methyl-methoxysilane, di(ethyl)-methyl-ethoxysilane, di(ethyl)-methyl-n-propoxysilane, di(ethyl)-methyl-iso-propoxysilane, Di(ethyl)methyl(n-butoxy)silane, Di(ethyl)methyl(sec-butoxy)silane, Di(ethyl)methyl(tert-butoxy)silane, Trimethyl(iso-propoxy)silane, Trimethyl(iso-butoxy)silane Silane, trimethyl(sec-butoxy)silane, trimethyl(n-butoxy)silane, trimethyl(tert-butoxy)silane, di(propyl)methyl(methoxy)silane, di(propyl)methyl(ethoxy)silane, di(propyl) methyl(propoxy)silane, di(propyl)methyl(iso-propoxy)silane, di(n-propyl)methyl(butoxy)silane, di(n-propyl)methyl(sec-butoxy)silane, di(n-propyl) methyl(tert-butoxy)silane, di(n-propyl)methyl(iso-butoxy)silane, di(iso-propyl)methyl(methoxy)silane, di(iso-propyl)methyl(ethoxy)silane, di(iso- propyl)methyl(propoxy)silane, di(iso-propyl)methyl(iso-propoxy)silane, di(iso-propyl)methyl(n-butoxy)silane, di(iso-propyl)methyl(sec-butoxy)silane, Di(iso-propyl)methyl(tert-butoxy)silane, di(iso-propyl)methyl(iso-butoxy)silane, di(methyl)ethyl(methoxy)silane, di(methyl)ethyl(ethoxy)silane, di( methyl)ethyl(n-propoxy)silane, di(methyl)ethyl(iso-propoxy)silane, di(methyl)ethyl(n-butoxy)silane, di(methyl)ethyl(sec-butoxy)silane, di(methyl) -ethyl-tert-butoxysilane, di(methyl)ethyl(iso-butoxy)silane, di(methyl)n-propyl(methoxy)silane, di(methyl)n-propyl(ethoxy)silane, di(methyl)n- propyl(n-propoxy)silane, di(methyl)n-propyl(iso-propoxy)silane, di(methyl)n-propyl(butoxy)silane, di(methyl)n-propyl(sec-butoxy)silane, di( methyl)n-propyl(tert-butoxy)silane, di(methyl)n-propyl di(iso-butoxy)silane, di(methyl)iso-propyl(methoxy)silane, di(methyl)iso-propyl(ethoxy)silane, di(methyl)iso-propyl(n-propoxy)silane, di(methyl) iso-propyl(iso-propoxy)silane, di(methyl)iso-propyl(n-butoxy)silane, di(methyl)iso-propyl(sec-butoxy)silane, di(methyl)iso-propyl(tert-butoxy) Silane, di(methyl)iso-propyl(iso-butoxy)silane, di(methyl)n-butyl(methoxy)silane, di(methyl)n-butyl(ethoxy)silane, di(methyl)n-butyl(propoxy) Silane, di(methyl)n-butyl(iso-propoxy)silane, di(methyl)n-butyl(n-butoxy)silane, di(methyl)-n-butyl(sec-butoxy)silane, di(methyl)n -butyl(tert-butoxy)silane, di(methyl)-n-butyl(iso-butoxy)silane, di(methyl)sec-butyl(methoxy)silane, di(methyl)sec-butyl(ethoxy)silane, di( methyl)sec-butyl(n-propoxy)silane, di(methyl)sec-butyl(iso-propoxy)silane, di(methyl)sec-butyl(n-butoxy)silane, di(methyl)sec-butyl(sec- butoxy)silane, di(methyl)sec-butyl(tert-butoxy)silane, di(methyl)sec-butyl(iso-butoxy)silane, di(methyl)tert-butyl(methoxy)silane, di(methyl)tert- Butyl(ethoxy)silane, di(methyl)tert-butyl(propoxy)silane, di(methyl)tert-butyl(iso-propoxy)silane, di(methyl)tert-butyl(n-butoxy)silane, di(methyl) at least one selected from the group consisting of tert-butyl(sec-butoxy)silane, di(methyl)tert-butyl(tert-butoxy)silane, di(methyl)tert-butyl(iso-butoxy)silane and combinations thereof 12. The composition of claim 11, comprising 12. The composition of claim 11, wherein said halide comprises chloride ions. 14. The composition of claim 13, wherein said chloride ion, if present, is present at a concentration of 50 ppm or less as measured by IC. 14. The composition of claim 13, wherein the chloride ion, if present, is present at a concentration of 10 ppm or less as measured by IC. 14. The composition of claim 13, wherein said chloride ion, if present, is present at a concentration of 5 ppm or less as measured by IC.

Images